Nickel electrodes are utilized in a number of electrochemical cells and batteries including nickel/zinc, nickel/hydrogen, nickel/iron and nickel/cadmium batteries. Such nickel electrodes may be formed in a variety of ways. One particularly useful and relatively inexpensive nickel electrode is the pressed nickel electrode which is made by pressing a mixture of active electrode material and binder into the openings in an apertured lightweight current collector.
The principal active electrode material may be nickel hydroxide or it may be NiO.sub.x which is a berthollide, i.e., x is not an integer. The NiO.sub.x is prepared by chemically oxidizing a nickelous compound such as nickel nitrate by reacting the latter with an oxidizing agent such as sodium hypochlorite in an alkaline medium. Analysis of the NiO.sub.x indicates that it has a nickel content of about 55% by weight and that the value of x is between about 1.65 and 1.8. Analysis also indicates that the NiO.sub.x probably includes some water of hydration.
It has been known that the charge acceptance of the aforementioned pressed nickel electrodes is improved by incorporating a cobalt-containing compound such as cobalt hydroxide in the active electrode material mixture. This is done by simply mixing the nickel-containing and cobalt-containing compounds together with the binder and pressing the resulting mixture into a current collector.
While these prior art pressed nickel electrodes generally exhibit good electrical characteristics, they have to be subjected to a number of charge/discharge cycles in order to obtain good charge acceptance, i.e., they have to be "formed" before using.